IPTV is a technology that provides television content over a packet switched network using the Internet Protocol. The network providing the television content can be a local area network, the Internet or any subnet. IPTV is a streaming format where a set of IPTV sources provide the IPTV content over the IPTV network to a set of subscribers using multicast streaming protocols. IPTV television content can include live television channels, time shifted television content, video on demand services and similar content. Any number of IPTV sources can provide the IPTV content over the IPTV network to any number of subscribers.
The Internet Group Management Protocol (IGMP) is an Internet protocol that is used by IPTV subscribers to join or leave a multicast group associated with an IPTV channel provided by an IPTV source. Group membership is established by use of membership reports and leave messages. This protocol defines membership report messages that function as join requests and leave messages and processes by which a subscriber can request that an IPTV channel be sent to the subscriber (membership report message) or to end the transmission of the IPTV channel to the subscriber (leave message).
The IGMP messages are generated by a set top box, an IPTV or similar client application associated with a subscriber. These messages can be generated in response to user input such as channel selection input through the set top box or the IPTV itself. The IGMP messages are sent toward an IPTV source connected to the set top box or IPTV via a multicast network or similar network. The IGMP message is initially processed by an edge router of this multicast network. The edge router runs a multicast routing protocol and maintains a set of multicast group membership lists. The multicast routing protocol communicates with the multicast network to promulgate the information to establish a multicast tree from the IPTV source to each of the edge routers that service subscribing set top boxes and IPTVs for each multicast group where each multicast group corresponds to an IPTV source and channel.
A loopback interface is a virtual interface that can be configured on a router. The loopback interface is not connected to any other device and is a virtual interface rather than a physical interface. Any forwarding associated with such a loopback interface is dropped at the router.